Question

Помогите, пожалуйста, с упрощением x1 и x2, все перепробовала, ничего не подходит

Answer 1

$ax^{2} + bx + c = 0\x^{2} - 2x - 1 = 0\ a = 1; b = -2; c = -1\D = b^{2} - 4ac = (-2)^{2} - 4 cdotp 1 cdotp (-1) = 4 + 4 = 8$

$x_{1} = dfrac{-b + sqrt{D}}{2a} = dfrac{2 + sqrt{8}}{2} = dfrac{2 + sqrt{4 cdotp 2}}{2} = dfrac{2 + 2sqrt{2}}{2} = dfrac{2(1 + sqrt{2})}{2} = 1 + sqrt{2}$

$x_{2} = dfrac{-b - sqrt{D}}{2a} = dfrac{2 - sqrt{8}}{2} = dfrac{2 - sqrt{4 cdotp 2}}{2} = dfrac{2 - 2sqrt{2}}{2} = dfrac{2(1 - sqrt{2})}{2} = 1 - sqrt{2}$

Answer 2

$x1 = frac{2 + sqrt{8} }{2} = frac{2 + sqrt{4 times 2} }{2} = \ frac{2 + 2 sqrt{2} }{2} = frac{2(1 + sqrt{2)} }{2} = \ 1 + sqrt{2} \ x2 = frac{2 - sqrt{8} }{2} = frac{2 - 2 sqrt{2} }{2} = \ frac{2(1 - sqrt{2)} }{2} = 1 - sqrt{2}$